1 School of Mechanics and Optoelectronic Physics, Anhui University of Science and Technology, Huainan 232001, China
2 State Key Laboratory of Safe Mining of Deep Coal and Environmental Protection, Anhui University of Science and Technology, Huainan 232001, China
3 State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui University of Science and Technology, Huainan 232001, China
To investigate the influence of high temperature on the sealing performance of mudstone caprock during underground coal gasification (UCG), experimental studies were conducted on the gas seepage behavior of mudstone under temperature-stress coupling conditions. The mudstone caprock from the Taiyuan Formation-Shanxi Formation coal seam roof in the Ordos Basin was used as the research object. The effects of temperature (20, 200, 400, and 600 ℃) on the physical properties and seepage behavior of the mudstone caprock were analyzed, and a mathematical model was established to describe the relationship between temperature-stress coupling and mudstone gas permeability. The results indicate that a critical temperature of 400 ℃ causes a significant change in the permeability behavior of mudstone. Compared with the condition below 400 ℃, the mass loss rate, elongation, thermal expansion coefficient, and gas permeability of the mudstone increase more markedly with rising temperature, and its mesostructure is more severely damaged. Beyond this critical temperature, the gas-sealing performance of the mudstone caprock is greatly reduced, which adversely affects the gas collection efficiency of the underground coal gasification chamber. The findings reveal the significance of temperature-stress coupling effects on the gas permeability of mudstone, which can provide an important theoretical foundation and parametric support for evaluating the sealing capacity of caprocks, predicting gas leakage risks, and controlling the stability of surrounding rocks under high-temperature disturbances during underground coal gasification (UCG). This holds practical implications for advancing the engineering application of UCG in China.
LUO Ji-an, GE Yu, DING Ke, REN Bo.
Experiment on Evolution of Permeability in Mudstone Caprock after High Temperature Cooling Treatment[J].
Science Technology and Engineering, 2026, 26(12): 5189-5196 DOI:10.12404/j.issn.1671-1815.2503643
综合已有研究可知,即使对于同类岩石,其在高温下的渗透行为也会因地质条件与应力状态的不同而呈现显著差异[14-19]。然而,目前针对泥岩盖层在高温与三轴应力共同作用下的渗透率演化研究仍相对不足[20-24]。为此,以鄂尔多斯盆地太原组-山西组煤层顶板盖层泥岩为研究对象,开展经20、200、400和600 ℃热处理后的三轴加载渗流实验,系统研究高温作用下泥岩盖层的物理与渗透特性。首先,分析热处理后泥岩试样的物理性质,包括质量损失率、伸长率及热膨胀系数等;其次,利用扫描电镜(scanning electron microscope,SEM)观测其微观结构演变;进而,基于三轴渗流实验数据,详细揭示不同温度处理后泥岩在全应力-应变过程中渗透率的演化规律。通过上述研究,最终建立温度与应力共同影响下泥岩渗透率的数学表征模型。为深部UCG工程在高温条件下的开采模拟与工程设计提供理论依据。
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